It's a boys' name. It always has been, although people have relatively recently started using it as a girls' name, posibly because of the US fondness for names like Bree and Audrey. I knew two elderly Aubreys - it's not my favourite name but it's a proper choice.

In America, Aubrey is commonly used as a girl's name. This doesn't mean that Aubrey is a girl's name. It's not, it's a boy's name that Americans use for girls. I have heard of American girls called Graham ffs.I have never heard of a British female Aubrey.